Construction of stoves, furnaces, central heating boilers or like apparatuses



Nov. 17, 1964 T. o. H. J. DORREN CONSTRUCTION OF STOVES, FURNACES, CENTRAL HEATING BOILERS 0R LIKE APPARATUSES 5 Sheets-Sheet 1 Filed Sept. 27, 1962 INVENTOR rn'aanl 'nnvnp Mann-war: pan?! ATTORNEY5 1964 T. o. H. J. DORREN 3,157,138

CONSTRUCTION OF STOVES, FURNACES, CENTRAL HEATING BOILERS OR LIKE APPARATUSES Filed Sept. 27, 1962 I5 Sheets-Sheet 2 INVENTOR rfltooa x on LP Manner 4w! DORE! BY WWW .72.

ATTORNEYS Nov. 17, 1964 T. o. H. J. DORREN CONSTRUCTION OF 3,157,138 STOVES. FURNACES, CENTRAL HEATING BOILERS 0R LIKE APPARATUSES 3 Sheets-Sheet 3 Filed Sept. 27, 1962 BEE EM m mm: I

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ATTORNEY 5 United States Patent r 3,157,138 EGNSTRUCTIGN Elli FaTGVES, FURNAQIES, CENTltr-ill HEATENG lltllLEItS Gilt LIKE APPARATUhES Theodoor @swald Hubert Jules Borren, Heerlen, Netherlands, assignor to NIV. Maatsehappij Tot Exploitatie Van Lirnhurgsche Steenlrolenmijnen, Genaarnd Oranje- Nassau Mig'nen, Heerlen, Netherlands, a corporation of the Net erlands Filed Sept. 27, 1962, Ser. No. 226,499 3 Qlahns. (Cl. Mil-29) The invention concerns a coal fired stove, furnace, central heating boiler, or like apparatus having, inside a casing a coal retaining container over and spaced from a grate, the space between the coal container and the grate providing the combustion zone to which air is supplied from below and from the sides of the combustion zone, the combustion or line gases being discharged at the base of the coal container. Such apparatuses are generally known and in use.

In practice it is known to design such a stove for special types and sizes of coal. Also known is the measure to adjust one stove to diiferent sizes of coal by adjusting the distance between the grate and the upper limit of the combustion zone. However, for smaller sizes, in particular for a class of from 50 to 250 mils, specific problems are encountered, in that the fire becomes uncontrollable, is sometimes choked and the efficiency is lowered sharply.

It is also known that coals having coking properties are not to he used, particularly in the fine sizes, since these coals tend to form bridges and prevent coal from lowering to the combustion zone, resulting in the extinction of the fire.

It should also-be considered known that coal fired stoves, furnaces, hot water boilers, etc. are particularly unpopular on account of formation of dust on removing the ashes and on account of the necessary frequency of cleaning out the ash-tray. This, coupled to the continuously required supervision and to the relative difiiculty to light such an apparatus when extinguished has given rise to the decreasing demand of coal for domestic use, notwithstanding its economic value per unit of heat.

The object of the present invention is to provide a stove, central heating boiler, or like apparatus adapted to burn a great variety of sizes of coal whether or not having coking properties.

Another object of the invention need provide a stove, central heating boiler, or like apparatus, which is to be cleaned less frequently during operation.

Other objects and advantages will be apparent from the following description of a preferred embodiment of the invention illustrated in the accompanying drawing.

FIG. 1 shows a vertical section of a central heating boiler according to the invention.

FIG. 2 shows a vertical section through the same boiler along the line II-II of FIGURE 1.

FIG. 3 is a front elevation of the boiler illustrated in the FIGURE 1 or 2.

FIG. 4 shows a horizontal section along the line IV-IV of FIG. 1.

FIG. 5 shows a horizontal section along the line V-V of FIG. 2.

FIG. 6 shows a side elevation of the boiler illustrated in the previous figures, seen along the arrow P in FIG. 3.

FIG. 7 is a plan view of a fuel bed supporting plate that may be positioned in the housing during ash removal.

As shown in FIG. 1 the central heating boiler according to the invention is composed of a casing 1 enclosing a coal container 2, the space between the casing and the coal container constituting a water jacket 3. Vertically below the coal container 2 is provided a, substantially horizontal grate4, the space between the grate and the base of the coal container constituting the combustion zone 5. To fill the coal container, a port 6 has been provided, to be closed by a. cover 7.

At the base of the coal container 2 there are provided substantially horizontal water tubes 8 extending across the whole width of the base of the coal container and interconnecting two opposed sides of thewater jacket 3. Also there are passages 9 interconnecting the zone 5 with combustion gas passages 10 located inside the water jacket 3. For practical purposes the two parts of the water jacket 3 separated by gas passage 10 are interconnected by tubes 11.

The gas passage 10 communicates with a heat exchanger generally indicated at 12, located in the upper part of the boiler. The'water circulation is maintained through a water inlet 13 connected to the lower part of the water jacket 3 and through the heat exchanger 12, and is discharged at the upper part of the heat exchanger 12 through a water outlet 14. Flue gases are discharged to the line through gas discharge 15.

Returning to the construction of the base of the coal container 2 it should be noted that apart from water tubes 8 there are provided spaced members supported by the water tubes 8 and composed of substantially vertical plate shaped members 16 located on top of inverted V- shaped channels 17, the channels running just above and parallel to the water tubes. The V-shaped channels could have any other shape, provided the upper extremeties are closed and the lower extrerneties above the water tubes 8 are open.

For material for the platelike members 16, advantageously steel is to beused. The material should have fairly good heat conducting properties, so as to pre-heat the coal above the combustion zone gradually.

In the illustrated preferred embodiment of the invention, grate 4 is made vertically adjustable for a reason later to be explained. For its vertical adjustability, the grate is movable inia housing 18 having. tapering walls opening to the lower side of the housing. The grate 4 is supported by arms 19 two of which are fixed to each of two shafts 20, the shafts being interconnected and synchronized by means of two toothed wheel sectors 21,

g at least one of which is hand operated by means of a vided a space 26 for a lever 22. The grate 4 is guided by means of extensions 23 welded to the grate and passing through slits 24 on opposed side walls of the housing 18. On one side, the lower extremeties of the slits 24 are closed off by a bar 25, welded or otherwise fixed to the side wall of the housing 18. Below the base of housing 13 there is propurpose to be explained later.

In the middle of the casing on one side, a cover 27 has been provided giving access to the central part of the furnace. air valve 28 to adjust the amount of air admitted to the furnace for the combustion. In the access to the upper part of the furnace, for practical reasons there is provided a removable grate 29, so as to prevent ashes from falling out. The lower part of the combustion zone 5 is entirely enclosed by a gated members to guide the burned ashes. The grate 34 is supported by housing 18. The housing 18 has been provided on two opposed sides with two channels 31 to admit the insertion of a plate 32 having a handle 33. Plate 32 has to be moved through an opening 34 in the housing,-the opening being adapted to be closed by a cover 35.

For adjustably moving the grate 4, as has been mentioned before, two shafts 20 are provided, said shafts being synchronized and interconnected by means of two engaging toothed wheel sectors 21, the shafts being In the cover 27 is provided an adjustable grate 30 having vertically elonenemas interconnected by a connecting rod 36, so as to keep the shafts 20 at a fixed distance. In addition there is provided a blocking strip 37, provided with holes 33 to receive a pin 39 (FIG. secured to lever 22.

For the adjustment of the primary air supply to the combustion zone, a connection can be provided, in a well known manner, between valve 28 and a thermostat to be put in a stud 40 located in the upper part of the heat exchanger.

Further a device has been provided to supply secondary air to gases leaving the combustion zone. To this effect, the lower extremity of the combustion gas passage is closed by a perforated plate 41 on which is lengthwise movable a covering plate 42 having equidistant perforations in accordance to the fixed lower plate 41.

Relative to fixed plate 41, the movable plate 42 is movable between two extreme positions in one of which the perforations in both plates are in register While in the other the perforations are closed.

The perforations in fixed plate 41 communicate with the space receiving primary air for the combustion.

Finally there is a cover 43 in the lower extremity of casing 1 to slidably close space 2e.

To operate the central heating boiler according to the invention the coal container 2 is loaded with coal through port 6, after which cover 7 is closed. Coal descending from coal container 2 to the combustion zone 5 is lit in the conventional way. Gases pass upward through the combustion zone and accumulate below the inverted V- shaped member 17 and are mixed with downwardly flowing gases resulting from the de-gassing of coal in the coal container which are withdrawn in a downward direction over and through the combustion zone to the discharge passages 9 from which the gases pass through discharge passages 10 to the heat exchanger and through discharge orifice to the flute. Primary air for the combustion passes through grate 4 and grate 30 to the combustion zone, secondary air passing from the space outside the grate through perforations in fixed base plates 41 of combustion gases passage 10 to burn combustible gases escaping in this passage.

After combustion has proceeded so far that the combustion zone 5 is almost entirely filled with burned ashes, the grate 4 is lowered by means of a movement of lever 22, so that fresh coal is permitted to descend between heat conducting members 16 and inverted V-shaped channels 17 to the combustion zone 5.

As is generally known, coking properties of coal are a consequence of certain compounds having a low melting point and becoming viscous at a certain temperature. These compounds, however, on decomposition by heat are decomposed into combustible gases and carbon. In practice the decomposition is performed at an elevated temperature, so that the coal fuses together, while gases escape. The final products are coke and gas. According to the invention, fusion of the coal does not take place notwithstanding coal normally having coking properties is used. This advantageous effect is the result of the plate like extensions of the inverted V-shaped channels; said plate like extensions preheat the coal and decompose the said compounds notwithstanding the fact that preheating only takes place slowly. By the time the coal descending from the coal container 2 has reached the combustion zone 5, coking properties of the coal have entirely disappeared. Therefore, coal descends completely loosely to the combustion zone. Gases developed during the decomposition are forced downward to the combustion zone, in that the coal container is only open towards the combustion zone.

Primary air passing by valve 28 penetrates into the combustion zone through grate 4 and vertical grates 30. After having been converted into gases by the combustion of coal the gases flow along water tubes 8 and accumulate below roof shaped inverted V-members. The ases are cooled by the water tubes, so as not the transmit too much heat to the heat conducting members 16. From the places of accumulation below the roof shaped members 17 gases are withdrawn at the extremities of these roof shaped members 17 in a downward direction towards the discharge passage 9. After leaving passages 9 after burning of the still present combustible gases is effected by the admission of secondary air through the perforations in base plate 4-1 of the gas passage 10. Entrained gases from the decomposition of the coal in the coal container are submitted to an additional cracking process by passing these gases together with the flue gases, through the combustion zone, before allowing them to escape through passages 9 to passages 10.

As combustion proceeds the space in the combustion zone becomes filled with ashes, which are compacted by the coal descending from coal container 2 into the combustion zone 5. After some time this descending motion becomes too slow to maintain the combustion. In other words, the combustion zone contains too much ashes. Temperature of the boiler drops, while the valve 28 stays entirely open. At this point, or before, the grate 4 is lowered by means of a short movement of lever 22, to give more space for coal in the combustion zone 5.

This lowering of grate 4- may continue until the grate has reached its lowest point, which is recognizable by the position of lever 22. The distance over which grate 4 has to be lowered may be chosen so that it normally takes a considerable time to fill this space.

When the ashes have to be removed, cover 35 is removed, and plate 32 is inserted through the opening 34 in the housing of the boiler and through channels 31, so as to support the material remaining in the combustion zone, just below the vertical grates 3t Hereafter grate 4- is lowered entirely, one side being supported y bar 25, so that grate 4 is tilted and cover 43 is removed to clean out the accumulated ashes. After removal of the ashes grate 4 is replaced in its horizontal position, the extensions 23 being placed in the slits 24 and lever 22 is brought to its initial position to which action the grate 4 is brought up to its highest position. Hereafter cover 43 at the base of the casing is replaced, plate 32. is withdrawn and cover 35 is replaced. The boiler, herewith, is ready for another long period of operation.

It should be understood that the presence of the water tubes 8 is of importance for transmitting heat out of the combustion zone and, accordingly, limiting the temperature of the heat conducting members. By the provision of the water tubes, the depth of the combustion zone is limited.

However, if the water tubes are omitted, the heat conducting members still operate, but the range or" coals tending coke that can be used is smaller. Without these water tubes, plates 16 will have to be higher, but without the tubes the invention is fully applicable to ordinary stoves.

It should be appreciated that in the apparatus described during operation of the boiler a great variety of qualities of coal or coke may be used. Because of the slowly lowering action of the grate 4 continuously the ashes are expanded and danger of choking of the fire in the combustion zone is almost entirely eliminated. Through this action the use of fine coal having a minimum grain size of as low as 50 mils is made possible. So it may be said that the combination of, in principal, the heat conducting members and the lowerability of the grate 4 allows the use of a great variety of sizes and qualities, practically the only exception being sizes larger than the spacing between the roof-like members 17, and of dust like material. Therefore, the boiler may be fired with virtually any material on the market which at the moment needed is most economic without having to adjust anything in the boiler.

In the apparatus according to the invention, all gases are perfectly burned so that no losses by incomplete combustion occur.

The use of the inverted V-shap'ed channels reduces the flow resistance of the gases to a great extent and, in addition, aids in causing a better combustion in the central part of the combustion zone, in that the tendency for the combustion air to say on the outside of the combustion zone is greatly reduced.

As to the function of the grate 4 it should be appreciated that this grate takes over the function of a conventional ashtray bottom. It should be noted that after having removed the ashes, the grate 4 is brought upward to a position in which it lies directly below ashes immediately following the combustion zone. On removing the auxiliary plate 32, burned ashes come to rest on the grate. Therefore, the grate is never in contact with the combustion zone proper, so that there is no danger of corrosion of the grate, which adds to the grate life, whereas no trouble is encountered on removing ashes from the grate. Also the ashes to be removed are always cooled, so that another source of heat losses is eliminated. A great advantage is also that the ashes should only be removed at extended intervals of time.

What I claim is:

1. A coal fired furnace or the like heating apparatus, comprising, in combination, a housing; a grate supported within said housing; a coal container positioned within said housing substantially above and in vertically spaced relation with said grate; means defining a combustion zone above said grate, said coal container communicating with said combustion zone to provide for passage of coal from said container into the combustion zone; flue gas discharge passage means communicating with said combustion zone adjacent the upper end thereof and below said coal container; means forming an adjustable combustion air inlet opening into said combustion zone; a plurality of heat conducting vertical plates arranged in horizontally spaced parallel relation to each other and extending transversely of said grate, said plates being positioned in vertically spaced relation with said grate and extending from the upper end of the combustion zone into said coal coutainer; each of said plates being formed with a downwardly opening channel-like means along its lower edge for restricting flow of coal from said container into said combustion zone and for entrapping hot combustion gases of said combustion zone for heating of said plates to impart heat to coal passing therebetween for degassing of the coal.

2. A coal fired furnace or the like heating apparatus, comprising, in combination, a housing; a grate supported within said housing; a coal container positioned within said housing above and in vertically spaced relation with said grate; means defining a combustion zone above said grate, said coal container communicating with said combustion zone for passage of coal from said container into said combustion zone; flue gas discharge passage means communicating with said combustion zone adjacent the upper end thereof and below said coal container; means forming an adjustable combustion air inlet to said combustion zone; a plurality of heat conducting vertical plates arranged in horizontally spaced parallel relation to each other to extend transversely of said grate and vertically spaced relation thereto, said plates extending vertically from the upper portion of said combustion zone into the coal container; means forming an inverted channel-like construction along the bottom edge of each plate to restrict passage of coal from said container into said combustion zone and to entrap heated combustion gases for heating of said plates to heat coal passing therebetween to degas the coal; and a plurality of liquid containing tubes each positioned at a small vertical distance below a respective channel construction with the axis of each tube lying in the plane of the associated vertical plate.

3. A coal fired furnace or the like heating apparatus, as claimed in claim 1, in which said grate is vertically adjustable.

4. A coal fired furnace or the like heating apparatus, as claimed in claim 3, said housing including a side wall formed with a substantially horizontally extending slot therein; a removable closure for said slot; said slot being located at a level just above the uppermost limit of p0sitioning of said grate; the two side walls or" said housing extending from said one side wall being provided with horizontally extending guide means along their inner surfaces and horizontally aligned with said slot; and a plate movable through said slot and along said guide means, upon opening of said removable closure, to support the fuel bed during removal of ashes from said grate.

5. A coal fired furnace or the like heating apparatus, as

claimed in claim 2, in which said grate is vertically adjustable.

6. A coal fired furnace or the like-heating apparatus, as claimed in claim 5, said housing including a side wall formed with a substantially horizontally extending slot therein; a removable closure for said slot; said slot being located at a level just above the uppermost limit of positioning of said grate; the two side walls of said housing extending from said one side wall being provided with horizontally extending guide means along their inner surface and horizontally aligned with said slot; and a plate movable through said slot and along said guide means upon opening of said removable closure to support the fuel bed during removal of ashes from said grate.

7. A coal fired furnace or the like heating apparatus, as claimed in claim 1, including means mounting said grate for adjustment vertically of said housing in the lower portion of the latter; a pair of shafts rotatably mounted in said housing and extending parallel to each other, each shaft extending along a respective one of a pair of opposite sides of said housing; a pair of arm means each having a fixed end secured to a respective one of said shafts and a free end engaged with said grate to support said grate for such vertical adjustment; a pair of intermeshing gears, each secured to one of said shafts, whereby said shafts are conjointly operable; an operating handle fixed to one of said gears for adjustment of the vertical position of said grate; and means selectively operable to latch said operating lever in one of a plurality of adjusted positions corresponding to a selected level of said grate.

8. A coal fired furnace or the like heating apparatus, as claimed in claim 2, including means mounting said grate for adjustment ventically of said housing in the lower portion of the latter; a pair of shafts rotatably mounted in said housing and extending parallel to each other, each shaft extending along a respective one of a pair of opposite sides of said housing; a pair of arm means each having a fixed end secured to a respective one of said shafts and a free end engaged with said grate to support said grate for such vertical adjustment; a pair of intermeshing gears, each secured to one of said shafts whereby said shafts are conjointly operable; an operating handle fixed to one of said gears for adjustment of the vertical position of said grate; and means selectively operable to latch said operating lever in one of a plurality of adjusted positions corresponding to a selected level of said grate.

References Cited in the file of this patent UNITED STATES PATENTS 50,613 Moss Oct. 14, 1865 946,310 Archer Jan. 11, 1910 1,899,424 Rodie Feb. 28, 1933 1,920,572 Lacke Aug. 1, 1933 2,039,423 Johnson et a1. May 5, 1936 2,047,579 Cross July 14, 1936 2,160,481 Lockwood May 30, 1939 2,317,838 West et a1. Apr. 27, 1943 FOREIGN PATENTS 29,062 Great Britain Dec. 13, 1909 284,759 Germany May 11, 1913 

1. A COAL FIRED FURNACE OR THE LIKE HEATING APPARATUS, COMPRISING, IN COMBINATION, A HOUSING; A GRATE SUPPORTED WITHIN SAID HOUSING; A COAL CONTAINER POSITIONED WITHIN SAID HOUSING SUBSTANTIALLY ABOVE AND IN VERTICALLY SPACED RELATION WITH SAID GRATE; MEANS DEFINING A COMBUSTION ZONE ABOVE SAID GRATE, SAID CKJOAL CONTAINER COMMUNICATING WITH SAID COMBUSTION ZONE TO PROVIDE FOR PASSAGE OF COAL FROM SAID CONTAINER INTO THE COMBUSTION ZONE; FLUE GAS DISCHARGE PASSAGE MEANS COMMUNICATING WITH SAID COMBUSTION ZONE ADJACENT THE UPPER END THEREOF AND BELOW SAID COAL CONTAINER; MEANS FORMING AN ADJUSTABLE COMBUSTION AIR INLET OPENING INTO SAID COMBUSTION ZONE; A PLURALITY OF HEAT CONDUCTING VERTICAL PLATES ARRANGED IN HORIZONTALLY SPACED PARALLEL RELATION TO EACH OTHER AND EXTENDING TRANSVERSELY OF SAID GRATE, SAID PLATES BEING POSITIONED IN VERTICALLY SPACED RELATION WITH SAID GRATE AND EXTENDING FROM THE UPPER END OF THE COMBUSTION ZONE INTO SAID COAL CONTAINER; EACH OF SAID PLATES BEING FORMED WITH A DOWNWARDLY OPENING CHANNEL-LIKE MEANS ALONG ITS LOWER EDGE FOR RESTRICTING FLOW OF COAL FROM SAID CONTAINER INTO SAID COMBUSTION ZONE AND FOR ENTRAPPING HOT COMBUSTION GASES OF SAID COMBUSTION ZONE FOR HEATING OF SAID PLATES TO IMPART HEAT TO COAL PASSING THEREBETWEEN FOR DEGASSING OF THE COAL. 